Radiolabeling and Isotopic Markers

All elements can exist as two or
more isotopes that differ in the number of neutrons in the nucleus. Some
isotopes are stable indefinitely, while others are unstable (radioactive).
Radioactive isotopes decay with a defined half-life, and primarily through
release of helium nuclei (α particles), electrons or positrons (β particles),
and γ radiation. The ready detection of this emitted radiation, even on a very
small scale, underlies the utility and high sensitivity of a radioactive label.

This website focuses on the isotopes primarily of interest to organic
chemists, which include the non-metal Main Group elements. Once prepared, radiolabeled compounds meet a variety of fates, but the
goal is ultimately to detect the labeled molecule, fragment or metabolite: a
suitable radiolabel or isotopic marker should allow normal chemical or biochemical processes to be monitored without
causing any interference.